In Sarah Polley’s Toronto-set drama “Take this Waltz,” Margo (Michelle Williams) stumbles across Daniel (Luke Kirby) on a business trip, only to find he lives across the street; despite being married to Lou (Seth Rogen), Margo can’t stop thinking of Daniel. Or maybe it’s because she’s married to Lou that she can’t stop thinking of Daniel … Following up “Away from Her,” Polley’s second film is sharply dividing critics and audience in Toronto: Many find it simultaneously exhilarating and depressing; others find it ugly and hateful; a third faction seems to be kicking against the film not for how it says what it says, but, instead, for what it says in the first place.

Like a modernist version of a late ’60s or early ’70s relationship film — “An Unmarried Woman,” or “Carnal Knowledge” or “Faces,” for example, “Take this Waltz” first takes nothing for granted, and then takes everything on. Is monogamy viable? Why do we give up the old for the new? Or why do we not when we should? Can we ever be completely happy? Is sex love?

If Polley’s second directorial effort were just talking, it would still be superb; a scene where Kirby explains, at her prompting, exactly what he’d do to (and with, and for) Williams while they sit over martinis in a public restaurant is the most achingly sexual and intimate scene at the movies in 2011, with not a single touch. (The way Williams says the word “No” alone late in that scene — first as a question, then as an answer — is achingly raw.) But Polley has also become, early in her career, a visualist and sensualist of the highest order. There are one or two mis-steps here, to be sure — a scene with a queeny, mincing aquarobics instructor and its denouement seem like they’re on loan from an Adam Sandler film; Sarah Silverman, as Rogen’s recovering alcoholic sister, is more a screen presence than an actor. And within the first 10 minutes, Williams has a speech about travel anxiety (“I’m … afraid of connections. In airports.”) that might as well have a light bulb-emblazoned sign reading “METAPHOR!” zoomed in on guywires. Those complaints, though, are only because the rest of this film is so good, and so strong, that they seem like cracks in a otherwise flawless creation. I cannot praise Williams and Rogen and the previously-unknown Kirby enough; I cannot convey to you the depths of Polley’s understanding (Polley knows that love is a conspiracy, and that there is no betrayal more traitorous than conspiring against your co-conspirator); I cannot convey the sense of heat and beauty in how Polley films Toronto’s streets and nights. And yet, “Take this Waltz” is also, for lack of a better words, infuriating and troubling — not because of what it gets ‘wrong,’ but because the things it gets right are buried under your skin like a splinter you can’t dislodge, tearing at the nerves and flesh. Critic Carina Chocano recently wrote a New York Times Magazine piece on how what the cinema needs, perhaps, are fewer “strong” female characters and more real female characters; this film serves as a demonstration of that idea. William’s Margo is deeply flawed, perhaps irredeemably broken, capable of monstrous selfishness in the search for happiness — and human, and as worthy of happiness as anyone. As we are. And Polley isn’t afraid of sex, nor is she banal enough to think it cures all ills, or that it can’t be used as a weapon. (Polley gets the sad fact only people who’ve been in ugly and protracted breakups know: Nothing could ever be more intimate than denying someone intimacy.) Before you think this all sounds dour and sour, though, also know that there are moments of laughter and joy here. Rogen subsumes his good humor into a performance — Lou, a cookbook writer, knows full well what his chicken-centered work-in-progress is doing to his life and diet — and there’s also a note of play here (even as it feeds into Polley’s theme of permanent adolescence and immaturity extending into our adult relationships); when Williams and Kirby taunt each other as ‘gaylords’ it’s horrible, real, immature and funny. And the films’ use of music — from a raucous party-scene Feist cover of Leonard Cohen‘s “Closing Time,” to a montage set to the Cohen song the film takes its title from depicting a relationship in fast-forward, hot sex and warm affection cooling to calm domesticity and freezing into half-aware snuggling while TV-watching — is excellent, with the exception of a pop-song from the past, used in two scenes, too good and brilliant and thematically appropriate and trashily perfect to name. Suffice it to say that Polley can find the pathos behind an ’80s one-hit wonder and turn that song’s dimwit chorus into an elegy on how time’s arrow moves only in one direction. Polley has an eye for detail and an ear for truth; at a press event for the film, she noted how she wanted to make her film go past where a conventional movie like this would end, showing what comes after, and that follow-through is what turns the film from a strong jab into a knockout punch. It may seem ridiculous to suggest that Polley, after only “Away from Her” and “Take this Waltz,” is one of Canada’s and film’s most exciting and important new directors; I’d suggest that contention only seems ridiculous if you haven’t yet seen “Take this Waltz.” [A]